Lawyers for Msgr. William J. Lynn have asked the Pennsylvania Supreme Court to reject prosecutors' appeal of a court decision that granted Lynn a new trial, calling the request "breathtakingly dishonest."
In court documents filed Tuesday, lawyers for Lynn, who was granted a new trial in December after being convicted for his role in supervising Catholic priests who molested children, contend that there are no grounds for appeal under state rules.
A Superior Court panel overturned Lynn's conviction and granted a new trial after finding that evidence about priests not involved in Lynn's case swayed the jury.
In its petition, filed less than two weeks ago, the Philadelphia District Attorney's Office argued that the jury needed to hear historical evidence of child abuse in the Archdiocese of Philadelphia.
But Lynn's attorney, Thomas A. Bergstrom, argued that the case does not meet the general standards for appeals because the Superior Court's decision was an unpublished opinion.
Rather, Bergstrom accused prosecutors of using emotions and the case's high profile to persuade the Supreme Court to hear the appeal, which he called "passion-based."
Lynn's petition also contends that the appeal hinges on "inaccurate, uncharged, and unproven allegations" about the Rev. Edward V. Avery, whom Lynn supervised.
"The level of unprofessionalism is alarming," Bergstrom wrote.
District Attorney Seth Williams has lauded the case, which was the country's first conviction of a Catholic Church leader related to covering up child sex abuse by priests.
Lynn, now 65, was sentenced in 2012 to three to six years in prison. He is being held at the state prison in Waymart, in northeastern Pennsylvania.